You draw a card at random from a deck that contains 3 black cards and 7 red cards.

What is P (draw a black card) ?

The P (draw a black card) is 3/10.

Step-by-step explanation:

It is given that the deck contains 3 black cards and 7 red cards.

Therefore, the total number of cards in the deck = 7 red + 3 black = 10 cards.

Now, we need to find the possible outcomes of getting a black card. So, the number of black cards in the deck = 3 black cards.

The formula to find the probability is given by:

Probability = Number of required event / Total number of outcomes.

Here, the required event is getting a black card out of 10 cards in the deck.

The number of required event is 3. The total number of outcomes is 10.

Probability (to draw black card) = 3/10.